This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. St Andrews has a strong instrumentation program in high field EPR, where much of the recent emphasis has been on the development of a high power kW pulse system at 94 GHz with very low deadtime, that was certainly partly inspired by much of the previous work at ACERT. Instrumentation was developed under a major UK Basic Technology program grant ([unreadable]2.6M) that also incorporated a major methodology/applications program with a focus on site-directed spin labelling that also used commercial X and Q-band instrumentation. The 94 GHz pulse spectrometer has now had circa 15 postdoc man years of hardware and software development and is a flexible and relatively easy to use instrument. Cornell and St Andrews are currently the only two groups in the world with pulse EPR instrumentation that operates at high (kW) powers at high fields. And, these are expensive programs, requiring major technical and developmental effort to develop flexible instrumentation, where small design decisions or changes in methodology can have major effects on practical usage and performance. A postdoctoral exchange program between Cornell and St Andrews is to be initiated. Such an exchange will focus on the following themes: 1) Comparative sensitivity measurements across different spectrometers, different frequencies and different pulse EPR methodologies e.g. comparison of double quantum and PELDOR measurements for long-range distance measurements 2) Exchange of ideas regarding high field instrument development and optimization of resonators and sample holders for different applications 3) Evaluation and optimization of best practice of sample preparation e.g. via the dramatic effect on TM on protein deuteration [unreadable]as opposed to solvent deuteration 4) Evaluation of new pulse methodologies e.g. using composite pulses or adiabatic pulses [unreadable]for which we have had some recent success. 5) Use and development of computer modelling packages e.g. for orientation selective PELDOR or motional studies.